Railroad experience has shown that preventing the uncoupling of railroad cars when trains are accidentally derailed, reduces the seriousness of the aftermath of such an incident. In particular, keeping the car in a train coupled together, controls three typical behavior patterns for derailed cars involved in an accident.
These behavior patterns include end puncture, pile up and rollover spills. By keeping the couplers engaged in the event of a derailment, it is less likely that the coupler from one car will ride up over the coupler of an adjacent car and puncture the end of the car upon coupler impact.
This hazard is especially serious in connection with tank cars where the puncture of the end of it by an adjacent coupler can release large amounts of hazardous material, thereby, creating a danger to life and property. When cars remain coupled together during derailment, it is less likely that they will pile up or domino. When pile ups do occur, the hazard of subsequent explosions and fires is greatly increased because fire or explosion in one car impinges on adjacent tanks and the effects are compounded.
When the cars remained coupled after a derailment, car rollovers tend to be prevented for the reason that the fastened coupler on an upright car tends to keep the adjacent car from tipping over. Here again the hazard is reduced which might otherwise be generated by material being spilled out of the manway of the car. Also, this minimizes the chance of damaging or shearing top fittings as a result of the car turning upside down.
Railway cars become separated or uncoupled in a train derailment because of vertical displacement between cars which permits the knuckles of mating couplers to disengage by sliding apart in a vertical direction. This is an unrestrained disengagement when the conventional type "E" coupler is employed. Most freight cars in the United States are so equipped. Various attempts have been made to maintain cars coupled in the event of a derailment. One form of car coupler presently being used is the type "F" coupler. The type "F" coupler is a special design to prevent vertical disengagement and is substantially more complicated than the type "E" coupler, since it is necessary to incorporate in it extra mechanical parts to provide for vertical and lateral displacement flexibility.
The type "F" coupler has many disadvantages. First, to perform the interlocking function in both upward and donward directions, mating type "F" couplers on the adjacent coupled cars are needed. When a type "F" coupler engages a type "E" coupler, the type "E" may move freely upward to the point of disengagement. As presently designed, the type "F" coupler cannot be installed readily on railroad cars presently in service. Thus, even if the type "F" coupler is installed on all new railroad cars, this will have only partial effect in improving the safety record of the many thousands of cars provided with the type "E" coupler, which currently are in service.
Secondly, the type "F" is significantly more expensive than the type "E" coupler to install initially on railroad cars. Since the type "F" coupler is more complicated, its maintenance cost is relatively high and its mechanical reliability is less favorable than for the simple type "E" coupler.
Numerous modifications were proposed for the type "E" coupler; however, none to date, have been commercially accepted.
Accordingly, it is an object of the present invention to provide a type "E" coupler having a means to prevent vertical disengagement of the knuckles.
Another object of the invention is to provide a coupler of the above type which, in addition, permits vertical angling.